Thermostat



April 1950 A. WILLIAMS, JR 2,505,599

THERMOSTAT Flled April 30, 1947 fkyw-y/z at S.

Patented Apr. 25, 1950 UNITED STATES PATENT OFFICE THERMOSTAT Lynn A. Williams, Jn, Indianapolis, Ind, as-

si nor to Stewart-Warner (Jorporation, Clai= care, BL, a corporation 05 Virginia Application April 36, 19%, Serial No. recess 1 Claim Ml. w ll- M The present invention relates to thermostats and more particularly to thermostats of the type which are actuated by the dissimilarity in the rate of expansion or difiereut metuls. One 01 the object of the present invention is to provide a novel low cost thermostat which is accurate and which responds almost instantaneously to changes in temperature.

A further object is to provide on improved the? mostat of the above type which particularly adaptable for use in liquid vessels while at the some time permitting the switch or other element which. is actuated by the thermostat to be located outside of the vessel. without the necessiy for pro viding any liquid see/Ls in the vessel well.

Still another object is to peovlde on improved thermostat which accomplishes the above, which develops considerable iforce end produces considemble motion without being heavy, cozelpllceted or expeusi @tloer objects end advantages will become parent from the following description of e. pr feared embodiment of my invention,

the drawings. in which similar characters of reference refer stroller parts throughout the several views, have illustrated o device embody lug one form of the invention l the dvruwlngs is e. somewhat dieerom mstic l'epresentetion of a. thermostat embodying the present invention shown from the side disposed within a liquid receptacle; and

Fig. is similar to the upper portion of l excep me that it is drawn to larger scale so as to indie c more clearly details of the invention.

.0. l of the drawings I have shown a. tool: or receptacle which may be considered as e portion of u hot water heater oi other receptacle containing water or other liquids to which the thermostat is to be responsive. As on example, this tank may be equipped with a cover l2 se= cured in place against a gasket 84 by screws [16. An L-shaped bracket H is secured to the upper surface of the cover 53 and is pivoted at 20 to a horizontal beam or bar 22, the opposite or free end of which is urged outwardly by e coil spring 24. This bar at a point near its free end is provided with an adjustment screw 26 which is threaded vertically therethrough and is so anranged that its lower end is adapted to operate on electric switch 28 or other element to be actuated whenever the free end of the bar has moved downwardly some predetermined amount.

The temperature responsive element of the thermostat comprises a length of capillary tubing 30 made of brass or some other metal bovine porti :2. ol tube, however, is some 2 e high coe'fidcieut of thermal. expansion. of this tube is disposed beneath the be: m

gully in place so es to prevezo. oleslreo no two ends 01 the tube may be placed adjacent each other as shown and secured by soldering throughout as cousid rcb h end portions of contsc with other and are sol cgether for e cousi- LhcJEQE-E distance loop o comparatively luege u loop is b around. and is soldered es the stand 3 portions oi the tube slifihtl,

the cover This gives a comparatively structuse end is easy fabricate. As wil be parent presently, the tube should be formed without causing sharp bends, but with this res= triction in mind the tubing may be bent to almost any desired shape, depending largely upon. the size and shape of the liquid vessel; and upon the length of tubing it is desired to dispose within the liquid space.

A small diameter wire so oi lover: or similar material which has a. very low coemcien of a, mel. expansion extends from end to em? the capillary tubing 3d so that both ends a wire project. A collar #32 is secured to one of these ends in any suitable manner and the other end of the wire is then pulled tight so as to draw the collar 42 against the end of the tube. The opposite or free end 01 the wire is then passed through an opening M in the bar 22 and throw e leaf spring 46 and is fitted at its upper end wltn a. second collar 48 or" any suitable type which secured tightly to the wire in contact with the upper surface of the spring 86.

Whenever the temperature oi the water or other liquid in the receptacle ll rises the tube so will expand whereas the wire 4t will expand a much less amount. Since the collar 42 ot move with respect to the end of the tube with which it is in contact, the wire will be drawn downwardly into the opposite end of the tube and therefore will pull downwardly on the switch bar 22 so as to operate the switch 20 at some predetermined temperature. Upon a decrease in the temperatureof the water the tube will contract, thereby permitting the end of the wire secured to the collar 48 to move upwardly under the infiuence of the spring 24 which raises the free end of the switch bar 22, thereby operating the elec tric switch in the opposite direction.

From the above description of a preferred embodiment of my invention it will be seen that a thermostat of this type may be manufactured at low cost and that no trouble with leakage at the soldered point 32 is likely to result. Further, substantially any degree of movement of the collar 48 with temperature change can be accomplished simply by increasing or decreasing the length of the tubing 30 and the wire which passes through this tubing. Because of the fact that the wire 40 is under tension at all times it may be of very small diameter since it need not be rigid as is true of the actuating element of some typ s of thermostats which maintain the low expansion element under compression.

Having described my invention, what I claim as new and useful'and desire to secure by Letters Patent of the United States is:

A thermostatic element adapted to be sensitive to the temperature of a liquid mass confined by a wall comprising a length of coiled capillary tubing submerged in said liquid and formed of a metal having a high coefficient of thermal ex- 4 pansion, both ends of said tubing being brought out through said wall in liquid-tight relation theretoga wire of a material having a low coemcient of thermal expansion extending through said tubing from end to end, both ends 01' said wire passing outwardly from the ends of said tubing, one end of said wire being iixed so that it cannot be retracted into said tubing, and movement responsive means connected between the other end of said tubing andthe other end of said wire whereby temperature changes of said tubing and said wire will cause relative expansion between said wire and said tubing so that the free end of said wire will move relative to its end of the tubing, and biasing means for pulling upon the free end of said wire for keeping said wire tight in said tubing. i

LYNN A. WILLIAMS, Ja;

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,472,725 McClure Oct. 30, 1923 1,599,208 Carpenter Sept. 7, 1926 1,782,458 Brennen Nov. 25, 1930 I FOREIGN PATENTS Number Country Date 517,012 Great Britain Jan. 1'7, 1940 600,471 France Nov. 9, 1925 

